diff --git a/docs/lib-shape_arc.md b/docs/lib-shape_arc.md
index 0408cf6c..5a909dab 100644
--- a/docs/lib-shape_arc.md
+++ b/docs/lib-shape_arc.md
@@ -1,6 +1,6 @@
 # shape_arc
 
-Returns shape points and triangle indexes of an arc shape. They can be used with xxx_extrude modules of dotSCAD. The shape points can be also used with the built-in polygon module. 
+Returns shape points of an arc shape. They can be used with xxx_extrude modules of dotSCAD. The shape points can be also used with the built-in polygon module. 
 
 ## Parameters